EUPREPIS ATLANTICUS (Noronha Skink). PREDATION

1 EUPREPIS ATLANTICUS (Noronha Skink). PREDATION. This lizard, formerly known as Mabuya maculata or M. punctata, is endemic to the Fernando de Noronha Archipelago off NE Brazil (Mausfeld and Vrcibradic 2002. J. Herpetol. 36:292-295; Mausfeld et al. 2002.

Zool. Anz. 241:281-293). It occurs across habitats from rocky seashore to insular forest, and thrives on a broad range of foods ranging flower nectar to human leftovers (IS, pers. observ.). No snakes or raptorial bird exist on the archipelago; thus, the Noronha skink likely evolved without native predators. The skink is well tolerated by humans; all houses harbor sizeable populations (up to 29 animals have been counted in a 6-room dwelling, IS pers. observ.). However, human colonization of archipelago has brought 3 rodent pests, brown (Rattus rattus) and Norway (Rattus norvegicus) rats, and house mice (Mus musculus) as well as animal pets, cats (Felis catus) and dogs (Canis domesticus). A few pairs of the giant tegu (Tupinambis merianae) were introduced in the 1950s for the alleged purpose of controlling rats and giant toads (Bufo paracnemis), the latter of which also represents an introduction.

Additionally, the cattle egret, already present in the 1980s, established breeding colonies in the archipelago by the year 2000 (JSM, pers. observ.). Herein, we report on predators of the Noronha skink as well as record cannibalism by this lizard (Table 1).

Except for the predation records by tegus, which we obtained from examination of gut contents, most predation records were direct visual observations. We obtained visual records opportunistically from June 2000 to January 2003, whereas tegu diet was studied from March 2000 to October 2001. Cats and egrets always stalked the skinks, whereas the tegu chased its prey - a hunting tactic it employs on smaller lizards (Sazima and Haddad 1992. In Morellato [ed.], Histรณria Natural da Serra do Japi, pp. 221-236. Edunicamp, Campinas). In the cannibalistic encounters, E. atlanticus adults robbed eggs from within shallow oviposition burrows of conspecifics, or chased smaller individuals often consuming their tail after a brief aggressive encounter. Cannibalism is recorded for the continental skink Mabuya

2 frenata (Vrcibradic and Rocha 1996. Herpetol. Rev. 27:201-202) and occurrence of this habit in E. atlanticus may be related both to its well developed opportunistic foraging behavior and high population densities (pers. observ.). One rat was found eating its prey during the day, but most probably took E. atlanticus in its nocturnal retreats. In all instances of consumption by rodents, the skink was already dead when the event was recorded, so it is unclear how frequently scavenging rather than actual predation occurs. As the house mouse was similar in size to the skink, a greater likelihood exists that consumption by house mice involves scavenging. We lack definitive data to support the view that any of the predators may be causing skink populations to decline on the archipelago. However, we noted that houses with resident cats have few or no skinks in their neighborhoods. A cat which give birth to four kitten weaned them with skinks, and we recorded eight skinks preyed on by this adult and seven ones by its kittens. Additionally, the toll taken by cattle egrets also may be high, as we recorded a single egret catching three skinks in a row during a foraging bout of about 10 min.

Submitted by JOSÉ MARTINS SILVA-JR., Centro Golfinho Rotador, CP 49, 53990000 Fernando de Noronha, Pernambuco, Brazil; AYRTON KLIER PÉRES-JR., Departamento de Zoologia, Universidade de Brasília, 70910-900 Brasília, DF, Brazil; IVAN SAZIMA, Departamento de Zoologia and Museu de História Natural, CP 6109, Universidade Estadual de Campinas, 13083-970 Campinas, São Paulo, Brazil.

Herpetological Review 36(1): 62-63.

3 TABLE 1. Predators of the Noronha skink (Euprepis atlanticus).

Predators

Records (n)

Comments

Felis catus (domestic cat)

23

Kittens killed, but did not eat 2 skinks

Mus musculus (house mouse)

1

Scavenging (?)

Rattus norvegicus (Norway rat)

2

Rattus rattus (black rat)

1

Bubulcus ibis (cattle egret)

11

Tupinambis merianae (tegu)

5

Actual predation event recorded once

Euprepis atlanticus (Noronha skink)

5

Eggs (2); juveniles (2); adult tail (1)

Herpetological Review 36(1):62-63.